Predicted Group 4 Tetra-azides M(N₃)₄(M = Ti−Hf, Th):  The First Examples of Linear M−NNN Coordination

Abstract

Quantum chemical calculations suggest that group 4 tetra-azides M(N 3 ) 4 , where M ) Ti, Zr, Hf, and Th, are stable species. They present a unique structural feature; namely, the M−N−N−N fragments are linear. These species are energetically more stable than the corresponding isomers with general formula η 5 -N 5 −M−η 7 -N 7 , and the Th species, Th(N 3 ) 4 , is the most stable of all. Possible mixed nitride azides NMN 3 were also investigated.

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

“…[31] These magnetic data provide clear evidence that complex 3 contains only U IV ions. The existence of mixed uranium nitrido/azido species had been predicted by quantum chemical calculations, [32] but only one example of such species has been previously isolated in the presence of supporting cyclopentadienyl ligands. [14] Complex 3 is thus a very rare example of a molecular azido/nitrido uranium cluster and is the first prepared without stabilizing ancillary ligands.…”

Preparation and Characterization of the First Binary Titanium Azides, Ti(N3)4, P(C6H5)4Ti(N3)5 and P(C6H5)42Ti(N3)6 and on Linear Ti-N-NN Coordination

“…The experimental vibrational spectra deviate significantly from those calculated for free Ti(N 3 ) 4 at the B3LYP level of theory, [8,16] and resemble those of higher-coordinated compounds with bent M-N-NN bonds. Therefore, the predicted [8] tetrahedral structure with linear Ti-N-NN bonds could not be confirmed in this study. The discrepancy between the calculated and observed spectra arises from solid state effects.…”

“…In a recent theoretical study, the group 4 metal tetrazides M(N3)4 (M = Ti, Zr, Hf, Th) were predicted [8] …”

“…In a recent theoretical study, the group 4 metal tetrazides M(N 3 ) 4 (M = Ti, Zr, Hf, Th) were predicted [8] to be vibrationally stable, exhibiting tetrahedral structures with unique linear M-N-NN bond angles (see Figure 1). All previously characterized covalent binary azide species possess bent M-N-NN angles.…”

Prediction of new inorganic molecules with quantum chemical methods

“…Other applications for metal azides are also known. We reported the results of a theoretical study of the metal tetra-azides M(N 3 ) 4 , where M=Ti, Zr, Hf, Th [51]. The molecules turned out to be stable with all frequencies real and they present a unique feature, namely the M-N-N-N structure is linear, giving the tetra-azides a tetrahedral shape (see Fig.…”